In the prior art, hybrid substrates, typically silicon-on-sapphire (SOS) substrates based on support substrates of sapphire having characteristics including good insulation, a high thermal conductivity, and a low loss in the radio-frequency band are used to construct devices for radio-frequency applications.
For the manufacture of SOS, heteroepitaxial growth of silicon on sapphire substrates is well known. This method has the drawback that many defects generate owing to the difference in lattice constant between sapphire and silicon (see Non-Patent Document 1, for example).
In view of the above problem, there was proposed a method comprising the steps of bonding a hydrogen ion-implanted silicon substrate to a sapphire substrate, making the hydrogen ion-implanted layer brittle, and separating the silicon substrate for thereby transferring a single crystal silicon thin film onto the sapphire substrate (see JP-A 2010-278337: Patent Document 1, for example).